#define  _CRT_SECURE_NO_WARNINGS 1
#include<iostream>
#include<stdio.h>
#include<stdlib.h>
using namespace std;
int main() {
	int a = 1;
	int& b = a;
	int& c = a;
	int d = 2;
	c = d;
	cout << a << endl;
	cout << b << endl;
	cout << c << endl;
	cout << d << endl;
	return 0;
}